The present invention relates to hook devices for use in assembling temporary scaffolds and built-in work platforms at construction sites.
Such hook devices are fixed to pipes, one at each end of the pipe, or to a scaffold board, in a pair to each of opposite ends of the board, and then removably fitted to other members fixed to the scaffold or work platform. Already known is a hook device which comprises a hook body having an inverted U-shaped inner peripheral surface formed by an upper wall, a front wall and a rear wall and fittable to a member to be connected, a stopper disposed in a stopper space formed in the hook body and having a retaining portion projectable beyond a lower end of the rear wall of the hook body toward a lower end of the front wall for preventing the hook body from slipping off the member to be connected by engagement therewith, the stopper being movable from a slipping-off preventing position to a slipping-off permitting position in which the retaining portion is positioned away from the lower end of the front wall to permit the hook body to slip off the member to be connected, an elastic member for biasing the stopper toward the slipping-off preventing position, and a connecting pin extending between and attached to opposite side walls of the hook body defining the stopper space for connecting together the hook body, the stopper and the elastic member, the connecting pin having an intermediate portion loosely inserted through a hole formed in the stopper to render the stopper pivotally movable about the axis of the connecting pin.
Although the stopper is required for the hook device to assure safety, the stopper will interfere with work, for example, when the temporary scaffold is disassembled. Stated more specifically, when the pipe or scaffold board provided with the hook device is to be removed, there arises a need to move the stopper to the slipping-off permitting position against the biasing force of the elastic member. Although immovable while being held by hand, the stopper returns to the slipping-off preventing position if released from the hand. It is therefore impossible to disassemble the scaffold or work platform by one person, hence the problem of a poor work efficiency.